1. Technical Field of the Invention
This invention relates to an amorphous transformer with a wound laminated core, and particularly to an amorphous transformer suitable for protecting the core from being damaged and for preventing fragments of amorphous metal from being scattered within coolant oil used to cool the transformer.
2. Description of Prior Art
A transformer has a core or cores forming a magnetic circuit and a coil or coils forming an electric circuit, for converting high voltage/small current alternating current (hereinafter AC) power into low voltage/large current AC power, or vice versa. As for the material of the core, some transformers have cores of amorphous ferromagnetic materials instead of oriented silicon steel. As for the construction of the amorphous metal core, wound laminated cores are used more often than stacked cores.
An example of an amorphous core transformer of the prior art with a wound laminated core is shown in FIGS. 21-24.
A basic construction of the amorphous transformer in the prior art is disclosed in FIGS. 21-23. In this prior art, the amorphous core transformer has a wound laminated core 1 of amorphous metal and a pair of coils 2, as disclosed in FIG. 22, only one of which is discussed in detail. The coil has an opening for inserting a leg portion of the wound laminated core 1. A coil frame 24 for winding the coil 2 thereon is disposed in the opening of the coil 2. As disclosed in FIG. 21, an amorphous sheet has a narrower width than that of a silicon steel sheet. However, in order to obtain a wider sectional area of the core 1 for use in large capacity transformers, two amorphous cores 11a and 11b are disposed side by side within the coil frame 24 as disclosed in FIG. 23. In such a construction, the longer side of the coil frame 24 is likely to be deflected by a force perpendicular to this side. When a large current such as a short-circuit current flows through the coil 2, an electro-magnetic repulsion force is generated between the inner winding 22 and the outer winding 21, between which is an insulation layer 23. The inner winding 22 is forced to move inward, which also forces the coil frame 24 to move inward and cause deflection as shown in FIG. 24. This deflection is transmitted to the amorphous cores 11a and 11b via spacers 3, which causes mechanical stress in the cores 11a, 11b.
In order to prevent the cores from being stressed as disclosed in prior art Japanese patent laid-open publication no. 63-193512 a construction using FRP plates or a plurality of laminated silicon steel plate are used as a reinforcement member disposed in such a manner that both ends thereof are abutted to the inner surface of a coil frame made of an insulating material. In general, insulating materials including FRP cause aged deterioration. In most cases, a decrease of volume occurs as aged deterioration occurs. When the volume of the coil frame decreases, a coil wound thereon becomes loosened and such undesirable phenomena as vibration or noise are likely to occur.